The demand for printed wiring boards for mounting electronic components such as IC (integrated circuits) tips and LSI (large-scale integrations) tips grows sharply with development of the electronics industry. With the required size and weight reduction and higher performance of electronic devices, film carrier tapes such as TAB tapes, COF tapes and T-BGA tapes are employed in the mounting of the electronic components. In particular, the film carrier tapes are of growing importance in the electronics industry where liquid crystal displays (LCD) such as personal computers are required for higher definition, thickness reduction and smaller frame area around the liquid crystal screen.
The film carrier tapes are generally quality inspected before and after electronic components such as semiconductors are mounted thereon. Specifically, appearance is visually checked by human eyes (a visual inspection using transmitted light or reflected light from the film carrier tape to be inspected) for defects in wiring patterns such as electrical disconnection, short-circuits, flaws and protrusions, defective plating, deformed tapes, imperfect solder resists and so on. Defective film carriers are marked using a defect marking device such as a punching device to form a hole mark or a stamping device to form an ink mark or using a magic marker.
Conventionally, inspection of the film carrier tapes has been carried out with an inspection apparatus as shown in FIG. 9 (see, for example, JP-A-2001-345345). The illustrated inspection apparatus 100 includes a feed device 102, an inspection part 110 and a take-up device 106.
The feed device 102 has a feed drive shaft 104 to which a feed reel 103 is attached. On the feed reel 103, a film carrier tape T for mounting electronic components (hereinafter, the film carrier tape T) is wound together with a spacer S. A drive motor (not shown) rotates the feed drive shaft 104 and thereby the film carrier tape T is fed together with the spacer S from the feed reel 103 and is transported to the inspection part 110 via a guide roller 115.
To inspect the film carrier tape T at the inspection part 110, a drive gear 122 that transports the film carrier tape T by engaging with sprocket holes of the tape T is temporarily stopped so that the film carrier tape T is exactly located at a predetermined inspection position. In the figure, the numeral 121 denotes a back tension device that applies back tension to the film carrier tape T being transported in a horizontal direction from upstream to downstream of the inspection part 110.
The inspection part 110 is equipped with a magnifier such as a microscope 111 for visual inspection using reflected or transmitted light for defects in wiring patterns such as electrical disconnection, short-circuits, flaws and protrusions, defective plating such as plating stain, deformation such as warpage of the tape, and imperfect solder resists such as scattered solder resists and pinholes. With the transportation of the film carrier tape T being suspended, one of wiring patterns arranged in line in a longer direction of the film carrier tape T is located at a predetermined inspection position and is visually inspected. When any defective parts are detected, they are marked as such by a defect marking device 112 by punching or ink marking.
After the visual inspection and the defect marking steps, the film carrier tape T is wound up on a take-up reel 107 attached to a take-up drive shaft 108 of a take-up device 106, via a guide roller 116. At the same time, the spacer S fed from the feed reel 103 via spacer guide rollers 117 and 118 is wound on the take-up reel 107. As a result, the film carrier tape T is wound around the take-up reel 107, with the spacer S interposing between the layers of tape wound on the take-up reel 107.
The numerals 125 and 126 denote dancer rollers that apply tension to the film carrier tape T being transported.
The wiring patterns on the film carrier tapes tend to be formed with finer pitches. When such fine-pitch patterns are visually inspected with the magnifier 111, the focal length of the lens needs to be shortened to ensure a required magnification for overall inspection of the wiring pattern. As shown in FIG. 8, the distance L from the eyepiece P1 to the inspection position P2 of the film carrier tape T is reduced.
When the distance L is reduced, that is, when the eyepiece P1 is lowered toward the floor on which the inspection apparatus 100 is placed, the inspector is caused to look through the eyepiece lenses in a forward leaning position rather than in a natural sitting position on a chair. For example, the film carrier tape and the lenses are about 21 cm apart when the magnification is 2.6×, but 4.1× magnification makes the distance between them 13 cm.
The visual inspection of the film carrier tape is performed with respect to wiring patterns that are arranged in a longer direction of the long tape wound on the feed reel 103. Therefore, the inspector has to maintain the forward leaning position over a long time. Further, microscopic foreign matters from the inspector will more likely fall on the inspected film carrier tape.
When a plurality of the film carrier tapes are inspected in parallel to each other at the inspection part across a large width of the tapes combined in the same field of view of the magnifier, the magnification is often lowered. In such cases, the focal length of the lenses is extended, and the distance L from the eyepiece P1 to the inspection position P2 of the film carrier tapes T increases as shown in FIG. 8. Because of this extended focal length, the inspector sitting on a chair of appropriate height is required to raise the seat height to conduct visual inspection through the eyepiece, which is unfavorable for safety reasons. In some cases, the eyepiece lenses can be raised so high that the inspector has to stand up to look through them. Because the visual inspection of the film carrier tape takes a long time as described above, such long inspection in a standing position causes undue fatigue to the inspector.
Furthermore, the visual inspection is generally carried out with a plurality of the inspection apparatuses 100 arranged in a room, so that it is preferred that each apparatus occupies a small space to effectively use the space inside the room.
The present invention has been made to solve the aforesaid problems of the prior art. It is therefore an object of the invention to provide an inspection apparatus and method for film carrier tapes for the mounting of electronic components and semiconductor devices whereby the inspector can conduct visual inspection of the film carrier tapes while sitting in a natural position on a chair of appropriate height regardless of the magnification of a magnifier, the inspection apparatus being compact to permit effective use of the space inside the inspection room.